1 /* $NetBSD: vfs_bio.c,v 1.231 2011/07/11 08:27:37 hannken Exp $ */ 2 3 /*- 4 * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Andrew Doran, and by Wasabi Systems, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /*- 33 * Copyright (c) 1982, 1986, 1989, 1993 34 * The Regents of the University of California. All rights reserved. 35 * (c) UNIX System Laboratories, Inc. 36 * All or some portions of this file are derived from material licensed 37 * to the University of California by American Telephone and Telegraph 38 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 39 * the permission of UNIX System Laboratories, Inc. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 3. Neither the name of the University nor the names of its contributors 50 * may be used to endorse or promote products derived from this software 51 * without specific prior written permission. 52 * 53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 63 * SUCH DAMAGE. 64 * 65 * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 66 */ 67 68 /*- 69 * Copyright (c) 1994 Christopher G. Demetriou 70 * 71 * Redistribution and use in source and binary forms, with or without 72 * modification, are permitted provided that the following conditions 73 * are met: 74 * 1. Redistributions of source code must retain the above copyright 75 * notice, this list of conditions and the following disclaimer. 76 * 2. Redistributions in binary form must reproduce the above copyright 77 * notice, this list of conditions and the following disclaimer in the 78 * documentation and/or other materials provided with the distribution. 79 * 3. All advertising materials mentioning features or use of this software 80 * must display the following acknowledgement: 81 * This product includes software developed by the University of 82 * California, Berkeley and its contributors. 83 * 4. Neither the name of the University nor the names of its contributors 84 * may be used to endorse or promote products derived from this software 85 * without specific prior written permission. 86 * 87 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 88 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 89 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 90 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 91 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 92 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 93 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 94 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 95 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 96 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 97 * SUCH DAMAGE. 98 * 99 * @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94 100 */ 101 102 /* 103 * The buffer cache subsystem. 104 * 105 * Some references: 106 * Bach: The Design of the UNIX Operating System (Prentice Hall, 1986) 107 * Leffler, et al.: The Design and Implementation of the 4.3BSD 108 * UNIX Operating System (Addison Welley, 1989) 109 * 110 * Locking 111 * 112 * There are three locks: 113 * - bufcache_lock: protects global buffer cache state. 114 * - BC_BUSY: a long term per-buffer lock. 115 * - buf_t::b_objlock: lock on completion (biowait vs biodone). 116 * 117 * For buffers associated with vnodes (a most common case) b_objlock points 118 * to the vnode_t::v_interlock. Otherwise, it points to generic buffer_lock. 119 * 120 * Lock order: 121 * bufcache_lock -> 122 * buf_t::b_objlock 123 */ 124 125 #include <sys/cdefs.h> 126 __KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.231 2011/07/11 08:27:37 hannken Exp $"); 127 128 #include "opt_bufcache.h" 129 130 #include <sys/param.h> 131 #include <sys/systm.h> 132 #include <sys/kernel.h> 133 #include <sys/proc.h> 134 #include <sys/buf.h> 135 #include <sys/vnode.h> 136 #include <sys/mount.h> 137 #include <sys/resourcevar.h> 138 #include <sys/sysctl.h> 139 #include <sys/conf.h> 140 #include <sys/kauth.h> 141 #include <sys/fstrans.h> 142 #include <sys/intr.h> 143 #include <sys/cpu.h> 144 #include <sys/wapbl.h> 145 146 #include <uvm/uvm.h> /* extern struct uvm uvm */ 147 148 #include <miscfs/specfs/specdev.h> 149 150 #ifndef BUFPAGES 151 # define BUFPAGES 0 152 #endif 153 154 #ifdef BUFCACHE 155 # if (BUFCACHE < 5) || (BUFCACHE > 95) 156 # error BUFCACHE is not between 5 and 95 157 # endif 158 #else 159 # define BUFCACHE 15 160 #endif 161 162 u_int nbuf; /* desired number of buffer headers */ 163 u_int bufpages = BUFPAGES; /* optional hardwired count */ 164 u_int bufcache = BUFCACHE; /* max % of RAM to use for buffer cache */ 165 166 /* Function prototypes */ 167 struct bqueue; 168 169 static void buf_setwm(void); 170 static int buf_trim(void); 171 static void *bufpool_page_alloc(struct pool *, int); 172 static void bufpool_page_free(struct pool *, void *); 173 static buf_t *bio_doread(struct vnode *, daddr_t, int, 174 kauth_cred_t, int); 175 static buf_t *getnewbuf(int, int, int); 176 static int buf_lotsfree(void); 177 static int buf_canrelease(void); 178 static u_long buf_mempoolidx(u_long); 179 static u_long buf_roundsize(u_long); 180 static void *buf_alloc(size_t); 181 static void buf_mrelease(void *, size_t); 182 static void binsheadfree(buf_t *, struct bqueue *); 183 static void binstailfree(buf_t *, struct bqueue *); 184 #ifdef DEBUG 185 static int checkfreelist(buf_t *, struct bqueue *, int); 186 #endif 187 static void biointr(void *); 188 static void biodone2(buf_t *); 189 static void bref(buf_t *); 190 static void brele(buf_t *); 191 static void sysctl_kern_buf_setup(void); 192 static void sysctl_vm_buf_setup(void); 193 194 /* 195 * Definitions for the buffer hash lists. 196 */ 197 #define BUFHASH(dvp, lbn) \ 198 (&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash]) 199 LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 200 u_long bufhash; 201 struct bqueue bufqueues[BQUEUES]; 202 203 static kcondvar_t needbuffer_cv; 204 205 /* 206 * Buffer queue lock. 207 */ 208 kmutex_t bufcache_lock; 209 kmutex_t buffer_lock; 210 211 /* Software ISR for completed transfers. */ 212 static void *biodone_sih; 213 214 /* Buffer pool for I/O buffers. */ 215 static pool_cache_t buf_cache; 216 static pool_cache_t bufio_cache; 217 218 /* XXX - somewhat gross.. */ 219 #if MAXBSIZE == 0x2000 220 #define NMEMPOOLS 5 221 #elif MAXBSIZE == 0x4000 222 #define NMEMPOOLS 6 223 #elif MAXBSIZE == 0x8000 224 #define NMEMPOOLS 7 225 #else 226 #define NMEMPOOLS 8 227 #endif 228 229 #define MEMPOOL_INDEX_OFFSET 9 /* smallest pool is 512 bytes */ 230 #if (1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) != MAXBSIZE 231 #error update vfs_bio buffer memory parameters 232 #endif 233 234 /* Buffer memory pools */ 235 static struct pool bmempools[NMEMPOOLS]; 236 237 static struct vm_map *buf_map; 238 239 /* 240 * Buffer memory pool allocator. 241 */ 242 static void * 243 bufpool_page_alloc(struct pool *pp, int flags) 244 { 245 246 return (void *)uvm_km_alloc(buf_map, 247 MAXBSIZE, MAXBSIZE, 248 ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT | UVM_KMF_TRYLOCK) 249 | UVM_KMF_WIRED); 250 } 251 252 static void 253 bufpool_page_free(struct pool *pp, void *v) 254 { 255 256 uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED); 257 } 258 259 static struct pool_allocator bufmempool_allocator = { 260 .pa_alloc = bufpool_page_alloc, 261 .pa_free = bufpool_page_free, 262 .pa_pagesz = MAXBSIZE, 263 }; 264 265 /* Buffer memory management variables */ 266 u_long bufmem_valimit; 267 u_long bufmem_hiwater; 268 u_long bufmem_lowater; 269 u_long bufmem; 270 271 /* 272 * MD code can call this to set a hard limit on the amount 273 * of virtual memory used by the buffer cache. 274 */ 275 int 276 buf_setvalimit(vsize_t sz) 277 { 278 279 /* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */ 280 if (sz < NMEMPOOLS * MAXBSIZE) 281 return EINVAL; 282 283 bufmem_valimit = sz; 284 return 0; 285 } 286 287 static void 288 buf_setwm(void) 289 { 290 291 bufmem_hiwater = buf_memcalc(); 292 /* lowater is approx. 2% of memory (with bufcache = 15) */ 293 #define BUFMEM_WMSHIFT 3 294 #define BUFMEM_HIWMMIN (64 * 1024 << BUFMEM_WMSHIFT) 295 if (bufmem_hiwater < BUFMEM_HIWMMIN) 296 /* Ensure a reasonable minimum value */ 297 bufmem_hiwater = BUFMEM_HIWMMIN; 298 bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT; 299 } 300 301 #ifdef DEBUG 302 int debug_verify_freelist = 0; 303 static int 304 checkfreelist(buf_t *bp, struct bqueue *dp, int ison) 305 { 306 buf_t *b; 307 308 if (!debug_verify_freelist) 309 return 1; 310 311 TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) { 312 if (b == bp) 313 return ison ? 1 : 0; 314 } 315 316 return ison ? 0 : 1; 317 } 318 #endif 319 320 /* 321 * Insq/Remq for the buffer hash lists. 322 * Call with buffer queue locked. 323 */ 324 static void 325 binsheadfree(buf_t *bp, struct bqueue *dp) 326 { 327 328 KASSERT(mutex_owned(&bufcache_lock)); 329 KASSERT(bp->b_freelistindex == -1); 330 TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist); 331 dp->bq_bytes += bp->b_bufsize; 332 bp->b_freelistindex = dp - bufqueues; 333 } 334 335 static void 336 binstailfree(buf_t *bp, struct bqueue *dp) 337 { 338 339 KASSERT(mutex_owned(&bufcache_lock)); 340 KASSERT(bp->b_freelistindex == -1); 341 TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist); 342 dp->bq_bytes += bp->b_bufsize; 343 bp->b_freelistindex = dp - bufqueues; 344 } 345 346 void 347 bremfree(buf_t *bp) 348 { 349 struct bqueue *dp; 350 int bqidx = bp->b_freelistindex; 351 352 KASSERT(mutex_owned(&bufcache_lock)); 353 354 KASSERT(bqidx != -1); 355 dp = &bufqueues[bqidx]; 356 KDASSERT(checkfreelist(bp, dp, 1)); 357 KASSERT(dp->bq_bytes >= bp->b_bufsize); 358 TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist); 359 dp->bq_bytes -= bp->b_bufsize; 360 361 /* For the sysctl helper. */ 362 if (bp == dp->bq_marker) 363 dp->bq_marker = NULL; 364 365 #if defined(DIAGNOSTIC) 366 bp->b_freelistindex = -1; 367 #endif /* defined(DIAGNOSTIC) */ 368 } 369 370 /* 371 * Add a reference to an buffer structure that came from buf_cache. 372 */ 373 static inline void 374 bref(buf_t *bp) 375 { 376 377 KASSERT(mutex_owned(&bufcache_lock)); 378 KASSERT(bp->b_refcnt > 0); 379 380 bp->b_refcnt++; 381 } 382 383 /* 384 * Free an unused buffer structure that came from buf_cache. 385 */ 386 static inline void 387 brele(buf_t *bp) 388 { 389 390 KASSERT(mutex_owned(&bufcache_lock)); 391 KASSERT(bp->b_refcnt > 0); 392 393 if (bp->b_refcnt-- == 1) { 394 buf_destroy(bp); 395 #ifdef DEBUG 396 memset((char *)bp, 0, sizeof(*bp)); 397 #endif 398 pool_cache_put(buf_cache, bp); 399 } 400 } 401 402 /* 403 * note that for some ports this is used by pmap bootstrap code to 404 * determine kva size. 405 */ 406 u_long 407 buf_memcalc(void) 408 { 409 u_long n; 410 411 /* 412 * Determine the upper bound of memory to use for buffers. 413 * 414 * - If bufpages is specified, use that as the number 415 * pages. 416 * 417 * - Otherwise, use bufcache as the percentage of 418 * physical memory. 419 */ 420 if (bufpages != 0) { 421 n = bufpages; 422 } else { 423 if (bufcache < 5) { 424 printf("forcing bufcache %d -> 5", bufcache); 425 bufcache = 5; 426 } 427 if (bufcache > 95) { 428 printf("forcing bufcache %d -> 95", bufcache); 429 bufcache = 95; 430 } 431 n = calc_cache_size(buf_map, bufcache, 432 (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT) 433 / PAGE_SIZE; 434 } 435 436 n <<= PAGE_SHIFT; 437 if (bufmem_valimit != 0 && n > bufmem_valimit) 438 n = bufmem_valimit; 439 440 return (n); 441 } 442 443 /* 444 * Initialize buffers and hash links for buffers. 445 */ 446 void 447 bufinit(void) 448 { 449 struct bqueue *dp; 450 int use_std; 451 u_int i; 452 453 mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE); 454 mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE); 455 cv_init(&needbuffer_cv, "needbuf"); 456 457 if (bufmem_valimit != 0) { 458 vaddr_t minaddr = 0, maxaddr; 459 buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr, 460 bufmem_valimit, 0, false, 0); 461 if (buf_map == NULL) 462 panic("bufinit: cannot allocate submap"); 463 } else 464 buf_map = kernel_map; 465 466 /* 467 * Initialize buffer cache memory parameters. 468 */ 469 bufmem = 0; 470 buf_setwm(); 471 472 /* On "small" machines use small pool page sizes where possible */ 473 use_std = (physmem < atop(16*1024*1024)); 474 475 /* 476 * Also use them on systems that can map the pool pages using 477 * a direct-mapped segment. 478 */ 479 #ifdef PMAP_MAP_POOLPAGE 480 use_std = 1; 481 #endif 482 483 buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 484 "bufpl", NULL, IPL_SOFTBIO, NULL, NULL, NULL); 485 bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0, 486 "biopl", NULL, IPL_BIO, NULL, NULL, NULL); 487 488 bufmempool_allocator.pa_backingmap = buf_map; 489 for (i = 0; i < NMEMPOOLS; i++) { 490 struct pool_allocator *pa; 491 struct pool *pp = &bmempools[i]; 492 u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET); 493 char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */ 494 if (__predict_true(size >= 1024)) 495 (void)snprintf(name, 8, "buf%dk", size / 1024); 496 else 497 (void)snprintf(name, 8, "buf%db", size); 498 pa = (size <= PAGE_SIZE && use_std) 499 ? &pool_allocator_nointr 500 : &bufmempool_allocator; 501 pool_init(pp, size, 0, 0, 0, name, pa, IPL_NONE); 502 pool_setlowat(pp, 1); 503 pool_sethiwat(pp, 1); 504 } 505 506 /* Initialize the buffer queues */ 507 for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) { 508 TAILQ_INIT(&dp->bq_queue); 509 dp->bq_bytes = 0; 510 } 511 512 /* 513 * Estimate hash table size based on the amount of memory we 514 * intend to use for the buffer cache. The average buffer 515 * size is dependent on our clients (i.e. filesystems). 516 * 517 * For now, use an empirical 3K per buffer. 518 */ 519 nbuf = (bufmem_hiwater / 1024) / 3; 520 bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash); 521 522 sysctl_kern_buf_setup(); 523 sysctl_vm_buf_setup(); 524 } 525 526 void 527 bufinit2(void) 528 { 529 530 biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr, 531 NULL); 532 if (biodone_sih == NULL) 533 panic("bufinit2: can't establish soft interrupt"); 534 } 535 536 static int 537 buf_lotsfree(void) 538 { 539 int try, thresh; 540 541 /* Always allocate if less than the low water mark. */ 542 if (bufmem < bufmem_lowater) 543 return 1; 544 545 /* Never allocate if greater than the high water mark. */ 546 if (bufmem > bufmem_hiwater) 547 return 0; 548 549 /* If there's anything on the AGE list, it should be eaten. */ 550 if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL) 551 return 0; 552 553 /* 554 * The probabily of getting a new allocation is inversely 555 * proportional to the current size of the cache, using 556 * a granularity of 16 steps. 557 */ 558 try = random() & 0x0000000fL; 559 560 /* Don't use "16 * bufmem" here to avoid a 32-bit overflow. */ 561 thresh = (bufmem - bufmem_lowater) / 562 ((bufmem_hiwater - bufmem_lowater) / 16); 563 564 if (try >= thresh) 565 return 1; 566 567 /* Otherwise don't allocate. */ 568 return 0; 569 } 570 571 /* 572 * Return estimate of bytes we think need to be 573 * released to help resolve low memory conditions. 574 * 575 * => called with bufcache_lock held. 576 */ 577 static int 578 buf_canrelease(void) 579 { 580 int pagedemand, ninvalid = 0; 581 582 KASSERT(mutex_owned(&bufcache_lock)); 583 584 if (bufmem < bufmem_lowater) 585 return 0; 586 587 if (bufmem > bufmem_hiwater) 588 return bufmem - bufmem_hiwater; 589 590 ninvalid += bufqueues[BQ_AGE].bq_bytes; 591 592 pagedemand = uvmexp.freetarg - uvmexp.free; 593 if (pagedemand < 0) 594 return ninvalid; 595 return MAX(ninvalid, MIN(2 * MAXBSIZE, 596 MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE))); 597 } 598 599 /* 600 * Buffer memory allocation helper functions 601 */ 602 static u_long 603 buf_mempoolidx(u_long size) 604 { 605 u_int n = 0; 606 607 size -= 1; 608 size >>= MEMPOOL_INDEX_OFFSET; 609 while (size) { 610 size >>= 1; 611 n += 1; 612 } 613 if (n >= NMEMPOOLS) 614 panic("buf mem pool index %d", n); 615 return n; 616 } 617 618 static u_long 619 buf_roundsize(u_long size) 620 { 621 /* Round up to nearest power of 2 */ 622 return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET)); 623 } 624 625 static void * 626 buf_alloc(size_t size) 627 { 628 u_int n = buf_mempoolidx(size); 629 void *addr; 630 631 while (1) { 632 addr = pool_get(&bmempools[n], PR_NOWAIT); 633 if (addr != NULL) 634 break; 635 636 /* No memory, see if we can free some. If so, try again */ 637 mutex_enter(&bufcache_lock); 638 if (buf_drain(1) > 0) { 639 mutex_exit(&bufcache_lock); 640 continue; 641 } 642 643 if (curlwp == uvm.pagedaemon_lwp) { 644 mutex_exit(&bufcache_lock); 645 return NULL; 646 } 647 648 /* Wait for buffers to arrive on the LRU queue */ 649 cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4); 650 mutex_exit(&bufcache_lock); 651 } 652 653 return addr; 654 } 655 656 static void 657 buf_mrelease(void *addr, size_t size) 658 { 659 660 pool_put(&bmempools[buf_mempoolidx(size)], addr); 661 } 662 663 /* 664 * bread()/breadn() helper. 665 */ 666 static buf_t * 667 bio_doread(struct vnode *vp, daddr_t blkno, int size, kauth_cred_t cred, 668 int async) 669 { 670 buf_t *bp; 671 struct mount *mp; 672 673 bp = getblk(vp, blkno, size, 0, 0); 674 675 #ifdef DIAGNOSTIC 676 if (bp == NULL) { 677 panic("bio_doread: no such buf"); 678 } 679 #endif 680 681 /* 682 * If buffer does not have data valid, start a read. 683 * Note that if buffer is BC_INVAL, getblk() won't return it. 684 * Therefore, it's valid if its I/O has completed or been delayed. 685 */ 686 if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) { 687 /* Start I/O for the buffer. */ 688 SET(bp->b_flags, B_READ | async); 689 if (async) 690 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 691 else 692 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 693 VOP_STRATEGY(vp, bp); 694 695 /* Pay for the read. */ 696 curlwp->l_ru.ru_inblock++; 697 } else if (async) 698 brelse(bp, 0); 699 700 if (vp->v_type == VBLK) 701 mp = vp->v_specmountpoint; 702 else 703 mp = vp->v_mount; 704 705 /* 706 * Collect statistics on synchronous and asynchronous reads. 707 * Reads from block devices are charged to their associated 708 * filesystem (if any). 709 */ 710 if (mp != NULL) { 711 if (async == 0) 712 mp->mnt_stat.f_syncreads++; 713 else 714 mp->mnt_stat.f_asyncreads++; 715 } 716 717 return (bp); 718 } 719 720 /* 721 * Read a disk block. 722 * This algorithm described in Bach (p.54). 723 */ 724 int 725 bread(struct vnode *vp, daddr_t blkno, int size, kauth_cred_t cred, 726 int flags, buf_t **bpp) 727 { 728 buf_t *bp; 729 int error; 730 731 /* Get buffer for block. */ 732 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 733 734 /* Wait for the read to complete, and return result. */ 735 error = biowait(bp); 736 if (error == 0 && (flags & B_MODIFY) != 0) 737 error = fscow_run(bp, true); 738 739 return error; 740 } 741 742 /* 743 * Read-ahead multiple disk blocks. The first is sync, the rest async. 744 * Trivial modification to the breada algorithm presented in Bach (p.55). 745 */ 746 int 747 breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks, 748 int *rasizes, int nrablks, kauth_cred_t cred, int flags, buf_t **bpp) 749 { 750 buf_t *bp; 751 int error, i; 752 753 bp = *bpp = bio_doread(vp, blkno, size, cred, 0); 754 755 /* 756 * For each of the read-ahead blocks, start a read, if necessary. 757 */ 758 mutex_enter(&bufcache_lock); 759 for (i = 0; i < nrablks; i++) { 760 /* If it's in the cache, just go on to next one. */ 761 if (incore(vp, rablks[i])) 762 continue; 763 764 /* Get a buffer for the read-ahead block */ 765 mutex_exit(&bufcache_lock); 766 (void) bio_doread(vp, rablks[i], rasizes[i], cred, B_ASYNC); 767 mutex_enter(&bufcache_lock); 768 } 769 mutex_exit(&bufcache_lock); 770 771 /* Otherwise, we had to start a read for it; wait until it's valid. */ 772 error = biowait(bp); 773 if (error == 0 && (flags & B_MODIFY) != 0) 774 error = fscow_run(bp, true); 775 return error; 776 } 777 778 /* 779 * Block write. Described in Bach (p.56) 780 */ 781 int 782 bwrite(buf_t *bp) 783 { 784 int rv, sync, wasdelayed; 785 struct vnode *vp; 786 struct mount *mp; 787 788 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 789 KASSERT(!cv_has_waiters(&bp->b_done)); 790 791 vp = bp->b_vp; 792 if (vp != NULL) { 793 KASSERT(bp->b_objlock == vp->v_interlock); 794 if (vp->v_type == VBLK) 795 mp = vp->v_specmountpoint; 796 else 797 mp = vp->v_mount; 798 } else { 799 mp = NULL; 800 } 801 802 if (mp && mp->mnt_wapbl) { 803 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 804 bdwrite(bp); 805 return 0; 806 } 807 } 808 809 /* 810 * Remember buffer type, to switch on it later. If the write was 811 * synchronous, but the file system was mounted with MNT_ASYNC, 812 * convert it to a delayed write. 813 * XXX note that this relies on delayed tape writes being converted 814 * to async, not sync writes (which is safe, but ugly). 815 */ 816 sync = !ISSET(bp->b_flags, B_ASYNC); 817 if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) { 818 bdwrite(bp); 819 return (0); 820 } 821 822 /* 823 * Collect statistics on synchronous and asynchronous writes. 824 * Writes to block devices are charged to their associated 825 * filesystem (if any). 826 */ 827 if (mp != NULL) { 828 if (sync) 829 mp->mnt_stat.f_syncwrites++; 830 else 831 mp->mnt_stat.f_asyncwrites++; 832 } 833 834 /* 835 * Pay for the I/O operation and make sure the buf is on the correct 836 * vnode queue. 837 */ 838 bp->b_error = 0; 839 wasdelayed = ISSET(bp->b_oflags, BO_DELWRI); 840 CLR(bp->b_flags, B_READ); 841 if (wasdelayed) { 842 mutex_enter(&bufcache_lock); 843 mutex_enter(bp->b_objlock); 844 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 845 reassignbuf(bp, bp->b_vp); 846 mutex_exit(&bufcache_lock); 847 } else { 848 curlwp->l_ru.ru_oublock++; 849 mutex_enter(bp->b_objlock); 850 CLR(bp->b_oflags, BO_DONE | BO_DELWRI); 851 } 852 if (vp != NULL) 853 vp->v_numoutput++; 854 mutex_exit(bp->b_objlock); 855 856 /* Initiate disk write. */ 857 if (sync) 858 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 859 else 860 BIO_SETPRIO(bp, BPRIO_TIMELIMITED); 861 862 VOP_STRATEGY(vp, bp); 863 864 if (sync) { 865 /* If I/O was synchronous, wait for it to complete. */ 866 rv = biowait(bp); 867 868 /* Release the buffer. */ 869 brelse(bp, 0); 870 871 return (rv); 872 } else { 873 return (0); 874 } 875 } 876 877 int 878 vn_bwrite(void *v) 879 { 880 struct vop_bwrite_args *ap = v; 881 882 return (bwrite(ap->a_bp)); 883 } 884 885 /* 886 * Delayed write. 887 * 888 * The buffer is marked dirty, but is not queued for I/O. 889 * This routine should be used when the buffer is expected 890 * to be modified again soon, typically a small write that 891 * partially fills a buffer. 892 * 893 * NB: magnetic tapes cannot be delayed; they must be 894 * written in the order that the writes are requested. 895 * 896 * Described in Leffler, et al. (pp. 208-213). 897 */ 898 void 899 bdwrite(buf_t *bp) 900 { 901 902 KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS || 903 bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE)); 904 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 905 KASSERT(!cv_has_waiters(&bp->b_done)); 906 907 /* If this is a tape block, write the block now. */ 908 if (bdev_type(bp->b_dev) == D_TAPE) { 909 bawrite(bp); 910 return; 911 } 912 913 if (wapbl_vphaswapbl(bp->b_vp)) { 914 struct mount *mp = wapbl_vptomp(bp->b_vp); 915 916 if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) { 917 WAPBL_ADD_BUF(mp, bp); 918 } 919 } 920 921 /* 922 * If the block hasn't been seen before: 923 * (1) Mark it as having been seen, 924 * (2) Charge for the write, 925 * (3) Make sure it's on its vnode's correct block list. 926 */ 927 KASSERT(bp->b_vp == NULL || bp->b_objlock == bp->b_vp->v_interlock); 928 929 if (!ISSET(bp->b_oflags, BO_DELWRI)) { 930 mutex_enter(&bufcache_lock); 931 mutex_enter(bp->b_objlock); 932 SET(bp->b_oflags, BO_DELWRI); 933 curlwp->l_ru.ru_oublock++; 934 reassignbuf(bp, bp->b_vp); 935 mutex_exit(&bufcache_lock); 936 } else { 937 mutex_enter(bp->b_objlock); 938 } 939 /* Otherwise, the "write" is done, so mark and release the buffer. */ 940 CLR(bp->b_oflags, BO_DONE); 941 mutex_exit(bp->b_objlock); 942 943 brelse(bp, 0); 944 } 945 946 /* 947 * Asynchronous block write; just an asynchronous bwrite(). 948 */ 949 void 950 bawrite(buf_t *bp) 951 { 952 953 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 954 KASSERT(bp->b_vp != NULL); 955 956 SET(bp->b_flags, B_ASYNC); 957 VOP_BWRITE(bp->b_vp, bp); 958 } 959 960 /* 961 * Release a buffer on to the free lists. 962 * Described in Bach (p. 46). 963 */ 964 void 965 brelsel(buf_t *bp, int set) 966 { 967 struct bqueue *bufq; 968 struct vnode *vp; 969 970 KASSERT(mutex_owned(&bufcache_lock)); 971 KASSERT(!cv_has_waiters(&bp->b_done)); 972 KASSERT(bp->b_refcnt > 0); 973 974 SET(bp->b_cflags, set); 975 976 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 977 KASSERT(bp->b_iodone == NULL); 978 979 /* Wake up any processes waiting for any buffer to become free. */ 980 cv_signal(&needbuffer_cv); 981 982 /* Wake up any proceeses waiting for _this_ buffer to become */ 983 if (ISSET(bp->b_cflags, BC_WANTED)) 984 CLR(bp->b_cflags, BC_WANTED|BC_AGE); 985 986 /* If it's clean clear the copy-on-write flag. */ 987 if (ISSET(bp->b_flags, B_COWDONE)) { 988 mutex_enter(bp->b_objlock); 989 if (!ISSET(bp->b_oflags, BO_DELWRI)) 990 CLR(bp->b_flags, B_COWDONE); 991 mutex_exit(bp->b_objlock); 992 } 993 994 /* 995 * Determine which queue the buffer should be on, then put it there. 996 */ 997 998 /* If it's locked, don't report an error; try again later. */ 999 if (ISSET(bp->b_flags, B_LOCKED)) 1000 bp->b_error = 0; 1001 1002 /* If it's not cacheable, or an error, mark it invalid. */ 1003 if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0) 1004 SET(bp->b_cflags, BC_INVAL); 1005 1006 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1007 /* 1008 * This is a delayed write buffer that was just flushed to 1009 * disk. It is still on the LRU queue. If it's become 1010 * invalid, then we need to move it to a different queue; 1011 * otherwise leave it in its current position. 1012 */ 1013 CLR(bp->b_cflags, BC_VFLUSH); 1014 if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) && 1015 !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) { 1016 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1)); 1017 goto already_queued; 1018 } else { 1019 bremfree(bp); 1020 } 1021 } 1022 1023 KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0)); 1024 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0)); 1025 KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0)); 1026 1027 if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) { 1028 /* 1029 * If it's invalid or empty, dissociate it from its vnode 1030 * and put on the head of the appropriate queue. 1031 */ 1032 if (ISSET(bp->b_flags, B_LOCKED)) { 1033 if (wapbl_vphaswapbl(vp = bp->b_vp)) { 1034 struct mount *mp = wapbl_vptomp(vp); 1035 1036 KASSERT(bp->b_iodone 1037 != mp->mnt_wapbl_op->wo_wapbl_biodone); 1038 WAPBL_REMOVE_BUF(mp, bp); 1039 } 1040 } 1041 1042 mutex_enter(bp->b_objlock); 1043 CLR(bp->b_oflags, BO_DONE|BO_DELWRI); 1044 if ((vp = bp->b_vp) != NULL) { 1045 KASSERT(bp->b_objlock == vp->v_interlock); 1046 reassignbuf(bp, bp->b_vp); 1047 brelvp(bp); 1048 mutex_exit(vp->v_interlock); 1049 } else { 1050 KASSERT(bp->b_objlock == &buffer_lock); 1051 mutex_exit(bp->b_objlock); 1052 } 1053 1054 if (bp->b_bufsize <= 0) 1055 /* no data */ 1056 goto already_queued; 1057 else 1058 /* invalid data */ 1059 bufq = &bufqueues[BQ_AGE]; 1060 binsheadfree(bp, bufq); 1061 } else { 1062 /* 1063 * It has valid data. Put it on the end of the appropriate 1064 * queue, so that it'll stick around for as long as possible. 1065 * If buf is AGE, but has dependencies, must put it on last 1066 * bufqueue to be scanned, ie LRU. This protects against the 1067 * livelock where BQ_AGE only has buffers with dependencies, 1068 * and we thus never get to the dependent buffers in BQ_LRU. 1069 */ 1070 if (ISSET(bp->b_flags, B_LOCKED)) { 1071 /* locked in core */ 1072 bufq = &bufqueues[BQ_LOCKED]; 1073 } else if (!ISSET(bp->b_cflags, BC_AGE)) { 1074 /* valid data */ 1075 bufq = &bufqueues[BQ_LRU]; 1076 } else { 1077 /* stale but valid data */ 1078 bufq = &bufqueues[BQ_AGE]; 1079 } 1080 binstailfree(bp, bufq); 1081 } 1082 already_queued: 1083 /* Unlock the buffer. */ 1084 CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE); 1085 CLR(bp->b_flags, B_ASYNC); 1086 cv_broadcast(&bp->b_busy); 1087 1088 if (bp->b_bufsize <= 0) 1089 brele(bp); 1090 } 1091 1092 void 1093 brelse(buf_t *bp, int set) 1094 { 1095 1096 mutex_enter(&bufcache_lock); 1097 brelsel(bp, set); 1098 mutex_exit(&bufcache_lock); 1099 } 1100 1101 /* 1102 * Determine if a block is in the cache. 1103 * Just look on what would be its hash chain. If it's there, return 1104 * a pointer to it, unless it's marked invalid. If it's marked invalid, 1105 * we normally don't return the buffer, unless the caller explicitly 1106 * wants us to. 1107 */ 1108 buf_t * 1109 incore(struct vnode *vp, daddr_t blkno) 1110 { 1111 buf_t *bp; 1112 1113 KASSERT(mutex_owned(&bufcache_lock)); 1114 1115 /* Search hash chain */ 1116 LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) { 1117 if (bp->b_lblkno == blkno && bp->b_vp == vp && 1118 !ISSET(bp->b_cflags, BC_INVAL)) { 1119 KASSERT(bp->b_objlock == vp->v_interlock); 1120 return (bp); 1121 } 1122 } 1123 1124 return (NULL); 1125 } 1126 1127 /* 1128 * Get a block of requested size that is associated with 1129 * a given vnode and block offset. If it is found in the 1130 * block cache, mark it as having been found, make it busy 1131 * and return it. Otherwise, return an empty block of the 1132 * correct size. It is up to the caller to insure that the 1133 * cached blocks be of the correct size. 1134 */ 1135 buf_t * 1136 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1137 { 1138 int err, preserve; 1139 buf_t *bp; 1140 1141 mutex_enter(&bufcache_lock); 1142 loop: 1143 bp = incore(vp, blkno); 1144 if (bp != NULL) { 1145 err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL); 1146 if (err != 0) { 1147 if (err == EPASSTHROUGH) 1148 goto loop; 1149 mutex_exit(&bufcache_lock); 1150 return (NULL); 1151 } 1152 KASSERT(!cv_has_waiters(&bp->b_done)); 1153 #ifdef DIAGNOSTIC 1154 if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) && 1155 bp->b_bcount < size && vp->v_type != VBLK) 1156 panic("getblk: block size invariant failed"); 1157 #endif 1158 bremfree(bp); 1159 preserve = 1; 1160 } else { 1161 if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL) 1162 goto loop; 1163 1164 if (incore(vp, blkno) != NULL) { 1165 /* The block has come into memory in the meantime. */ 1166 brelsel(bp, 0); 1167 goto loop; 1168 } 1169 1170 LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash); 1171 bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno; 1172 mutex_enter(vp->v_interlock); 1173 bgetvp(vp, bp); 1174 mutex_exit(vp->v_interlock); 1175 preserve = 0; 1176 } 1177 mutex_exit(&bufcache_lock); 1178 1179 /* 1180 * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes) 1181 * if we re-size buffers here. 1182 */ 1183 if (ISSET(bp->b_flags, B_LOCKED)) { 1184 KASSERT(bp->b_bufsize >= size); 1185 } else { 1186 if (allocbuf(bp, size, preserve)) { 1187 mutex_enter(&bufcache_lock); 1188 LIST_REMOVE(bp, b_hash); 1189 mutex_exit(&bufcache_lock); 1190 brelse(bp, BC_INVAL); 1191 return NULL; 1192 } 1193 } 1194 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1195 return (bp); 1196 } 1197 1198 /* 1199 * Get an empty, disassociated buffer of given size. 1200 */ 1201 buf_t * 1202 geteblk(int size) 1203 { 1204 buf_t *bp; 1205 int error; 1206 1207 mutex_enter(&bufcache_lock); 1208 while ((bp = getnewbuf(0, 0, 0)) == NULL) 1209 ; 1210 1211 SET(bp->b_cflags, BC_INVAL); 1212 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1213 mutex_exit(&bufcache_lock); 1214 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1215 error = allocbuf(bp, size, 0); 1216 KASSERT(error == 0); 1217 return (bp); 1218 } 1219 1220 /* 1221 * Expand or contract the actual memory allocated to a buffer. 1222 * 1223 * If the buffer shrinks, data is lost, so it's up to the 1224 * caller to have written it out *first*; this routine will not 1225 * start a write. If the buffer grows, it's the callers 1226 * responsibility to fill out the buffer's additional contents. 1227 */ 1228 int 1229 allocbuf(buf_t *bp, int size, int preserve) 1230 { 1231 void *addr; 1232 vsize_t oldsize, desired_size; 1233 int oldcount; 1234 int delta; 1235 1236 desired_size = buf_roundsize(size); 1237 if (desired_size > MAXBSIZE) 1238 printf("allocbuf: buffer larger than MAXBSIZE requested"); 1239 1240 oldcount = bp->b_bcount; 1241 1242 bp->b_bcount = size; 1243 1244 oldsize = bp->b_bufsize; 1245 if (oldsize == desired_size) { 1246 /* 1247 * Do not short cut the WAPBL resize, as the buffer length 1248 * could still have changed and this would corrupt the 1249 * tracking of the transaction length. 1250 */ 1251 goto out; 1252 } 1253 1254 /* 1255 * If we want a buffer of a different size, re-allocate the 1256 * buffer's memory; copy old content only if needed. 1257 */ 1258 addr = buf_alloc(desired_size); 1259 if (addr == NULL) 1260 return ENOMEM; 1261 if (preserve) 1262 memcpy(addr, bp->b_data, MIN(oldsize,desired_size)); 1263 if (bp->b_data != NULL) 1264 buf_mrelease(bp->b_data, oldsize); 1265 bp->b_data = addr; 1266 bp->b_bufsize = desired_size; 1267 1268 /* 1269 * Update overall buffer memory counter (protected by bufcache_lock) 1270 */ 1271 delta = (long)desired_size - (long)oldsize; 1272 1273 mutex_enter(&bufcache_lock); 1274 if ((bufmem += delta) > bufmem_hiwater) { 1275 /* 1276 * Need to trim overall memory usage. 1277 */ 1278 while (buf_canrelease()) { 1279 if (curcpu()->ci_schedstate.spc_flags & 1280 SPCF_SHOULDYIELD) { 1281 mutex_exit(&bufcache_lock); 1282 preempt(); 1283 mutex_enter(&bufcache_lock); 1284 } 1285 if (buf_trim() == 0) 1286 break; 1287 } 1288 } 1289 mutex_exit(&bufcache_lock); 1290 1291 out: 1292 if (wapbl_vphaswapbl(bp->b_vp)) 1293 WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount); 1294 1295 return 0; 1296 } 1297 1298 /* 1299 * Find a buffer which is available for use. 1300 * Select something from a free list. 1301 * Preference is to AGE list, then LRU list. 1302 * 1303 * Called with the buffer queues locked. 1304 * Return buffer locked. 1305 */ 1306 buf_t * 1307 getnewbuf(int slpflag, int slptimeo, int from_bufq) 1308 { 1309 buf_t *bp; 1310 struct vnode *vp; 1311 1312 start: 1313 KASSERT(mutex_owned(&bufcache_lock)); 1314 1315 /* 1316 * Get a new buffer from the pool. 1317 */ 1318 if (!from_bufq && buf_lotsfree()) { 1319 mutex_exit(&bufcache_lock); 1320 bp = pool_cache_get(buf_cache, PR_NOWAIT); 1321 if (bp != NULL) { 1322 memset((char *)bp, 0, sizeof(*bp)); 1323 buf_init(bp); 1324 SET(bp->b_cflags, BC_BUSY); /* mark buffer busy */ 1325 mutex_enter(&bufcache_lock); 1326 #if defined(DIAGNOSTIC) 1327 bp->b_freelistindex = -1; 1328 #endif /* defined(DIAGNOSTIC) */ 1329 return (bp); 1330 } 1331 mutex_enter(&bufcache_lock); 1332 } 1333 1334 KASSERT(mutex_owned(&bufcache_lock)); 1335 if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL || 1336 (bp = TAILQ_FIRST(&bufqueues[BQ_LRU].bq_queue)) != NULL) { 1337 KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH)); 1338 bremfree(bp); 1339 1340 /* Buffer is no longer on free lists. */ 1341 SET(bp->b_cflags, BC_BUSY); 1342 } else { 1343 /* 1344 * XXX: !from_bufq should be removed. 1345 */ 1346 if (!from_bufq || curlwp != uvm.pagedaemon_lwp) { 1347 /* wait for a free buffer of any kind */ 1348 if ((slpflag & PCATCH) != 0) 1349 (void)cv_timedwait_sig(&needbuffer_cv, 1350 &bufcache_lock, slptimeo); 1351 else 1352 (void)cv_timedwait(&needbuffer_cv, 1353 &bufcache_lock, slptimeo); 1354 } 1355 return (NULL); 1356 } 1357 1358 #ifdef DIAGNOSTIC 1359 if (bp->b_bufsize <= 0) 1360 panic("buffer %p: on queue but empty", bp); 1361 #endif 1362 1363 if (ISSET(bp->b_cflags, BC_VFLUSH)) { 1364 /* 1365 * This is a delayed write buffer being flushed to disk. Make 1366 * sure it gets aged out of the queue when it's finished, and 1367 * leave it off the LRU queue. 1368 */ 1369 CLR(bp->b_cflags, BC_VFLUSH); 1370 SET(bp->b_cflags, BC_AGE); 1371 goto start; 1372 } 1373 1374 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1375 KASSERT(bp->b_refcnt > 0); 1376 KASSERT(!cv_has_waiters(&bp->b_done)); 1377 1378 /* 1379 * If buffer was a delayed write, start it and return NULL 1380 * (since we might sleep while starting the write). 1381 */ 1382 if (ISSET(bp->b_oflags, BO_DELWRI)) { 1383 /* 1384 * This buffer has gone through the LRU, so make sure it gets 1385 * reused ASAP. 1386 */ 1387 SET(bp->b_cflags, BC_AGE); 1388 mutex_exit(&bufcache_lock); 1389 bawrite(bp); 1390 mutex_enter(&bufcache_lock); 1391 return (NULL); 1392 } 1393 1394 vp = bp->b_vp; 1395 1396 /* clear out various other fields */ 1397 bp->b_cflags = BC_BUSY; 1398 bp->b_oflags = 0; 1399 bp->b_flags = 0; 1400 bp->b_dev = NODEV; 1401 bp->b_blkno = 0; 1402 bp->b_lblkno = 0; 1403 bp->b_rawblkno = 0; 1404 bp->b_iodone = 0; 1405 bp->b_error = 0; 1406 bp->b_resid = 0; 1407 bp->b_bcount = 0; 1408 1409 LIST_REMOVE(bp, b_hash); 1410 1411 /* Disassociate us from our vnode, if we had one... */ 1412 if (vp != NULL) { 1413 mutex_enter(vp->v_interlock); 1414 brelvp(bp); 1415 mutex_exit(vp->v_interlock); 1416 } 1417 1418 return (bp); 1419 } 1420 1421 /* 1422 * Attempt to free an aged buffer off the queues. 1423 * Called with queue lock held. 1424 * Returns the amount of buffer memory freed. 1425 */ 1426 static int 1427 buf_trim(void) 1428 { 1429 buf_t *bp; 1430 long size = 0; 1431 1432 KASSERT(mutex_owned(&bufcache_lock)); 1433 1434 /* Instruct getnewbuf() to get buffers off the queues */ 1435 if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL) 1436 return 0; 1437 1438 KASSERT((bp->b_cflags & BC_WANTED) == 0); 1439 size = bp->b_bufsize; 1440 bufmem -= size; 1441 if (size > 0) { 1442 buf_mrelease(bp->b_data, size); 1443 bp->b_bcount = bp->b_bufsize = 0; 1444 } 1445 /* brelse() will return the buffer to the global buffer pool */ 1446 brelsel(bp, 0); 1447 return size; 1448 } 1449 1450 int 1451 buf_drain(int n) 1452 { 1453 int size = 0, sz; 1454 1455 KASSERT(mutex_owned(&bufcache_lock)); 1456 1457 while (size < n && bufmem > bufmem_lowater) { 1458 sz = buf_trim(); 1459 if (sz <= 0) 1460 break; 1461 size += sz; 1462 } 1463 1464 return size; 1465 } 1466 1467 /* 1468 * Wait for operations on the buffer to complete. 1469 * When they do, extract and return the I/O's error value. 1470 */ 1471 int 1472 biowait(buf_t *bp) 1473 { 1474 1475 KASSERT(ISSET(bp->b_cflags, BC_BUSY)); 1476 KASSERT(bp->b_refcnt > 0); 1477 1478 mutex_enter(bp->b_objlock); 1479 while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) 1480 cv_wait(&bp->b_done, bp->b_objlock); 1481 mutex_exit(bp->b_objlock); 1482 1483 return bp->b_error; 1484 } 1485 1486 /* 1487 * Mark I/O complete on a buffer. 1488 * 1489 * If a callback has been requested, e.g. the pageout 1490 * daemon, do so. Otherwise, awaken waiting processes. 1491 * 1492 * [ Leffler, et al., says on p.247: 1493 * "This routine wakes up the blocked process, frees the buffer 1494 * for an asynchronous write, or, for a request by the pagedaemon 1495 * process, invokes a procedure specified in the buffer structure" ] 1496 * 1497 * In real life, the pagedaemon (or other system processes) wants 1498 * to do async stuff to, and doesn't want the buffer brelse()'d. 1499 * (for swap pager, that puts swap buffers on the free lists (!!!), 1500 * for the vn device, that puts allocated buffers on the free lists!) 1501 */ 1502 void 1503 biodone(buf_t *bp) 1504 { 1505 int s; 1506 1507 KASSERT(!ISSET(bp->b_oflags, BO_DONE)); 1508 1509 if (cpu_intr_p()) { 1510 /* From interrupt mode: defer to a soft interrupt. */ 1511 s = splvm(); 1512 TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq); 1513 softint_schedule(biodone_sih); 1514 splx(s); 1515 } else { 1516 /* Process now - the buffer may be freed soon. */ 1517 biodone2(bp); 1518 } 1519 } 1520 1521 static void 1522 biodone2(buf_t *bp) 1523 { 1524 void (*callout)(buf_t *); 1525 1526 mutex_enter(bp->b_objlock); 1527 /* Note that the transfer is done. */ 1528 if (ISSET(bp->b_oflags, BO_DONE)) 1529 panic("biodone2 already"); 1530 CLR(bp->b_flags, B_COWDONE); 1531 SET(bp->b_oflags, BO_DONE); 1532 BIO_SETPRIO(bp, BPRIO_DEFAULT); 1533 1534 /* Wake up waiting writers. */ 1535 if (!ISSET(bp->b_flags, B_READ)) 1536 vwakeup(bp); 1537 1538 if ((callout = bp->b_iodone) != NULL) { 1539 /* Note callout done, then call out. */ 1540 KASSERT(!cv_has_waiters(&bp->b_done)); 1541 KERNEL_LOCK(1, NULL); /* XXXSMP */ 1542 bp->b_iodone = NULL; 1543 mutex_exit(bp->b_objlock); 1544 (*callout)(bp); 1545 KERNEL_UNLOCK_ONE(NULL); /* XXXSMP */ 1546 } else if (ISSET(bp->b_flags, B_ASYNC)) { 1547 /* If async, release. */ 1548 KASSERT(!cv_has_waiters(&bp->b_done)); 1549 mutex_exit(bp->b_objlock); 1550 brelse(bp, 0); 1551 } else { 1552 /* Otherwise just wake up waiters in biowait(). */ 1553 cv_broadcast(&bp->b_done); 1554 mutex_exit(bp->b_objlock); 1555 } 1556 } 1557 1558 static void 1559 biointr(void *cookie) 1560 { 1561 struct cpu_info *ci; 1562 buf_t *bp; 1563 int s; 1564 1565 ci = curcpu(); 1566 1567 while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) { 1568 KASSERT(curcpu() == ci); 1569 1570 s = splvm(); 1571 bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone); 1572 TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq); 1573 splx(s); 1574 1575 biodone2(bp); 1576 } 1577 } 1578 1579 /* 1580 * Wait for all buffers to complete I/O 1581 * Return the number of "stuck" buffers. 1582 */ 1583 int 1584 buf_syncwait(void) 1585 { 1586 buf_t *bp; 1587 int iter, nbusy, nbusy_prev = 0, dcount, ihash; 1588 1589 dcount = 10000; 1590 for (iter = 0; iter < 20;) { 1591 mutex_enter(&bufcache_lock); 1592 nbusy = 0; 1593 for (ihash = 0; ihash < bufhash+1; ihash++) { 1594 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1595 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY) 1596 nbusy += ((bp->b_flags & B_READ) == 0); 1597 } 1598 } 1599 mutex_exit(&bufcache_lock); 1600 1601 if (nbusy == 0) 1602 break; 1603 if (nbusy_prev == 0) 1604 nbusy_prev = nbusy; 1605 printf("%d ", nbusy); 1606 kpause("bflush", false, MAX(1, hz / 25 * iter), NULL); 1607 if (nbusy >= nbusy_prev) /* we didn't flush anything */ 1608 iter++; 1609 else 1610 nbusy_prev = nbusy; 1611 } 1612 1613 if (nbusy) { 1614 #if defined(DEBUG) || defined(DEBUG_HALT_BUSY) 1615 printf("giving up\nPrinting vnodes for busy buffers\n"); 1616 for (ihash = 0; ihash < bufhash+1; ihash++) { 1617 LIST_FOREACH(bp, &bufhashtbl[ihash], b_hash) { 1618 if ((bp->b_cflags & (BC_BUSY|BC_INVAL)) == BC_BUSY && 1619 (bp->b_flags & B_READ) == 0) 1620 vprint(NULL, bp->b_vp); 1621 } 1622 } 1623 #endif 1624 } 1625 1626 return nbusy; 1627 } 1628 1629 static void 1630 sysctl_fillbuf(buf_t *i, struct buf_sysctl *o) 1631 { 1632 1633 o->b_flags = i->b_flags | i->b_cflags | i->b_oflags; 1634 o->b_error = i->b_error; 1635 o->b_prio = i->b_prio; 1636 o->b_dev = i->b_dev; 1637 o->b_bufsize = i->b_bufsize; 1638 o->b_bcount = i->b_bcount; 1639 o->b_resid = i->b_resid; 1640 o->b_addr = PTRTOUINT64(i->b_data); 1641 o->b_blkno = i->b_blkno; 1642 o->b_rawblkno = i->b_rawblkno; 1643 o->b_iodone = PTRTOUINT64(i->b_iodone); 1644 o->b_proc = PTRTOUINT64(i->b_proc); 1645 o->b_vp = PTRTOUINT64(i->b_vp); 1646 o->b_saveaddr = PTRTOUINT64(i->b_saveaddr); 1647 o->b_lblkno = i->b_lblkno; 1648 } 1649 1650 #define KERN_BUFSLOP 20 1651 static int 1652 sysctl_dobuf(SYSCTLFN_ARGS) 1653 { 1654 buf_t *bp; 1655 struct buf_sysctl bs; 1656 struct bqueue *bq; 1657 char *dp; 1658 u_int i, op, arg; 1659 size_t len, needed, elem_size, out_size; 1660 int error, elem_count, retries; 1661 1662 if (namelen == 1 && name[0] == CTL_QUERY) 1663 return (sysctl_query(SYSCTLFN_CALL(rnode))); 1664 1665 if (namelen != 4) 1666 return (EINVAL); 1667 1668 retries = 100; 1669 retry: 1670 dp = oldp; 1671 len = (oldp != NULL) ? *oldlenp : 0; 1672 op = name[0]; 1673 arg = name[1]; 1674 elem_size = name[2]; 1675 elem_count = name[3]; 1676 out_size = MIN(sizeof(bs), elem_size); 1677 1678 /* 1679 * at the moment, these are just "placeholders" to make the 1680 * API for retrieving kern.buf data more extensible in the 1681 * future. 1682 * 1683 * XXX kern.buf currently has "netbsd32" issues. hopefully 1684 * these will be resolved at a later point. 1685 */ 1686 if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL || 1687 elem_size < 1 || elem_count < 0) 1688 return (EINVAL); 1689 1690 error = 0; 1691 needed = 0; 1692 sysctl_unlock(); 1693 mutex_enter(&bufcache_lock); 1694 for (i = 0; i < BQUEUES; i++) { 1695 bq = &bufqueues[i]; 1696 TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) { 1697 bq->bq_marker = bp; 1698 if (len >= elem_size && elem_count > 0) { 1699 sysctl_fillbuf(bp, &bs); 1700 mutex_exit(&bufcache_lock); 1701 error = copyout(&bs, dp, out_size); 1702 mutex_enter(&bufcache_lock); 1703 if (error) 1704 break; 1705 if (bq->bq_marker != bp) { 1706 /* 1707 * This sysctl node is only for 1708 * statistics. Retry; if the 1709 * queue keeps changing, then 1710 * bail out. 1711 */ 1712 if (retries-- == 0) { 1713 error = EAGAIN; 1714 break; 1715 } 1716 mutex_exit(&bufcache_lock); 1717 goto retry; 1718 } 1719 dp += elem_size; 1720 len -= elem_size; 1721 } 1722 needed += elem_size; 1723 if (elem_count > 0 && elem_count != INT_MAX) 1724 elem_count--; 1725 } 1726 if (error != 0) 1727 break; 1728 } 1729 mutex_exit(&bufcache_lock); 1730 sysctl_relock(); 1731 1732 *oldlenp = needed; 1733 if (oldp == NULL) 1734 *oldlenp += KERN_BUFSLOP * sizeof(buf_t); 1735 1736 return (error); 1737 } 1738 1739 static int 1740 sysctl_bufvm_update(SYSCTLFN_ARGS) 1741 { 1742 int t, error, rv; 1743 struct sysctlnode node; 1744 1745 node = *rnode; 1746 node.sysctl_data = &t; 1747 t = *(int *)rnode->sysctl_data; 1748 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1749 if (error || newp == NULL) 1750 return (error); 1751 1752 if (t < 0) 1753 return EINVAL; 1754 if (rnode->sysctl_data == &bufcache) { 1755 if (t > 100) 1756 return (EINVAL); 1757 bufcache = t; 1758 buf_setwm(); 1759 } else if (rnode->sysctl_data == &bufmem_lowater) { 1760 if (bufmem_hiwater - t < 16) 1761 return (EINVAL); 1762 bufmem_lowater = t; 1763 } else if (rnode->sysctl_data == &bufmem_hiwater) { 1764 if (t - bufmem_lowater < 16) 1765 return (EINVAL); 1766 bufmem_hiwater = t; 1767 } else 1768 return (EINVAL); 1769 1770 /* Drain until below new high water mark */ 1771 sysctl_unlock(); 1772 mutex_enter(&bufcache_lock); 1773 while ((t = bufmem - bufmem_hiwater) >= 0) { 1774 rv = buf_drain(t / (2 * 1024)); 1775 if (rv <= 0) 1776 break; 1777 } 1778 mutex_exit(&bufcache_lock); 1779 sysctl_relock(); 1780 1781 return 0; 1782 } 1783 1784 static struct sysctllog *vfsbio_sysctllog; 1785 1786 static void 1787 sysctl_kern_buf_setup(void) 1788 { 1789 1790 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1791 CTLFLAG_PERMANENT, 1792 CTLTYPE_NODE, "kern", NULL, 1793 NULL, 0, NULL, 0, 1794 CTL_KERN, CTL_EOL); 1795 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1796 CTLFLAG_PERMANENT, 1797 CTLTYPE_NODE, "buf", 1798 SYSCTL_DESCR("Kernel buffer cache information"), 1799 sysctl_dobuf, 0, NULL, 0, 1800 CTL_KERN, KERN_BUF, CTL_EOL); 1801 } 1802 1803 static void 1804 sysctl_vm_buf_setup(void) 1805 { 1806 1807 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1808 CTLFLAG_PERMANENT, 1809 CTLTYPE_NODE, "vm", NULL, 1810 NULL, 0, NULL, 0, 1811 CTL_VM, CTL_EOL); 1812 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1813 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1814 CTLTYPE_INT, "bufcache", 1815 SYSCTL_DESCR("Percentage of physical memory to use for " 1816 "buffer cache"), 1817 sysctl_bufvm_update, 0, &bufcache, 0, 1818 CTL_VM, CTL_CREATE, CTL_EOL); 1819 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1820 CTLFLAG_PERMANENT|CTLFLAG_READONLY, 1821 CTLTYPE_INT, "bufmem", 1822 SYSCTL_DESCR("Amount of kernel memory used by buffer " 1823 "cache"), 1824 NULL, 0, &bufmem, 0, 1825 CTL_VM, CTL_CREATE, CTL_EOL); 1826 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1827 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1828 CTLTYPE_INT, "bufmem_lowater", 1829 SYSCTL_DESCR("Minimum amount of kernel memory to " 1830 "reserve for buffer cache"), 1831 sysctl_bufvm_update, 0, &bufmem_lowater, 0, 1832 CTL_VM, CTL_CREATE, CTL_EOL); 1833 sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL, 1834 CTLFLAG_PERMANENT|CTLFLAG_READWRITE, 1835 CTLTYPE_INT, "bufmem_hiwater", 1836 SYSCTL_DESCR("Maximum amount of kernel memory to use " 1837 "for buffer cache"), 1838 sysctl_bufvm_update, 0, &bufmem_hiwater, 0, 1839 CTL_VM, CTL_CREATE, CTL_EOL); 1840 } 1841 1842 #ifdef DEBUG 1843 /* 1844 * Print out statistics on the current allocation of the buffer pool. 1845 * Can be enabled to print out on every ``sync'' by setting "syncprt" 1846 * in vfs_syscalls.c using sysctl. 1847 */ 1848 void 1849 vfs_bufstats(void) 1850 { 1851 int i, j, count; 1852 buf_t *bp; 1853 struct bqueue *dp; 1854 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 1855 static const char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE" }; 1856 1857 for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) { 1858 count = 0; 1859 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1860 counts[j] = 0; 1861 TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) { 1862 counts[bp->b_bufsize/PAGE_SIZE]++; 1863 count++; 1864 } 1865 printf("%s: total-%d", bname[i], count); 1866 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 1867 if (counts[j] != 0) 1868 printf(", %d-%d", j * PAGE_SIZE, counts[j]); 1869 printf("\n"); 1870 } 1871 } 1872 #endif /* DEBUG */ 1873 1874 /* ------------------------------ */ 1875 1876 buf_t * 1877 getiobuf(struct vnode *vp, bool waitok) 1878 { 1879 buf_t *bp; 1880 1881 bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT)); 1882 if (bp == NULL) 1883 return bp; 1884 1885 buf_init(bp); 1886 1887 if ((bp->b_vp = vp) == NULL) 1888 bp->b_objlock = &buffer_lock; 1889 else 1890 bp->b_objlock = vp->v_interlock; 1891 1892 return bp; 1893 } 1894 1895 void 1896 putiobuf(buf_t *bp) 1897 { 1898 1899 buf_destroy(bp); 1900 pool_cache_put(bufio_cache, bp); 1901 } 1902 1903 /* 1904 * nestiobuf_iodone: b_iodone callback for nested buffers. 1905 */ 1906 1907 void 1908 nestiobuf_iodone(buf_t *bp) 1909 { 1910 buf_t *mbp = bp->b_private; 1911 int error; 1912 int donebytes; 1913 1914 KASSERT(bp->b_bcount <= bp->b_bufsize); 1915 KASSERT(mbp != bp); 1916 1917 error = bp->b_error; 1918 if (bp->b_error == 0 && 1919 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 1920 /* 1921 * Not all got transfered, raise an error. We have no way to 1922 * propagate these conditions to mbp. 1923 */ 1924 error = EIO; 1925 } 1926 1927 donebytes = bp->b_bufsize; 1928 1929 putiobuf(bp); 1930 nestiobuf_done(mbp, donebytes, error); 1931 } 1932 1933 /* 1934 * nestiobuf_setup: setup a "nested" buffer. 1935 * 1936 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 1937 * => 'bp' should be a buffer allocated by getiobuf. 1938 * => 'offset' is a byte offset in the master buffer. 1939 * => 'size' is a size in bytes of this nested buffer. 1940 */ 1941 1942 void 1943 nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size) 1944 { 1945 const int b_read = mbp->b_flags & B_READ; 1946 struct vnode *vp = mbp->b_vp; 1947 1948 KASSERT(mbp->b_bcount >= offset + size); 1949 bp->b_vp = vp; 1950 bp->b_dev = mbp->b_dev; 1951 bp->b_objlock = mbp->b_objlock; 1952 bp->b_cflags = BC_BUSY; 1953 bp->b_flags = B_ASYNC | b_read; 1954 bp->b_iodone = nestiobuf_iodone; 1955 bp->b_data = (char *)mbp->b_data + offset; 1956 bp->b_resid = bp->b_bcount = size; 1957 bp->b_bufsize = bp->b_bcount; 1958 bp->b_private = mbp; 1959 BIO_COPYPRIO(bp, mbp); 1960 if (!b_read && vp != NULL) { 1961 mutex_enter(vp->v_interlock); 1962 vp->v_numoutput++; 1963 mutex_exit(vp->v_interlock); 1964 } 1965 } 1966 1967 /* 1968 * nestiobuf_done: propagate completion to the master buffer. 1969 * 1970 * => 'donebytes' specifies how many bytes in the 'mbp' is completed. 1971 * => 'error' is an errno(2) that 'donebytes' has been completed with. 1972 */ 1973 1974 void 1975 nestiobuf_done(buf_t *mbp, int donebytes, int error) 1976 { 1977 1978 if (donebytes == 0) { 1979 return; 1980 } 1981 mutex_enter(mbp->b_objlock); 1982 KASSERT(mbp->b_resid >= donebytes); 1983 mbp->b_resid -= donebytes; 1984 if (error) 1985 mbp->b_error = error; 1986 if (mbp->b_resid == 0) { 1987 if (mbp->b_error) 1988 mbp->b_resid = mbp->b_bcount; 1989 mutex_exit(mbp->b_objlock); 1990 biodone(mbp); 1991 } else 1992 mutex_exit(mbp->b_objlock); 1993 } 1994 1995 void 1996 buf_init(buf_t *bp) 1997 { 1998 1999 cv_init(&bp->b_busy, "biolock"); 2000 cv_init(&bp->b_done, "biowait"); 2001 bp->b_dev = NODEV; 2002 bp->b_error = 0; 2003 bp->b_flags = 0; 2004 bp->b_cflags = 0; 2005 bp->b_oflags = 0; 2006 bp->b_objlock = &buffer_lock; 2007 bp->b_iodone = NULL; 2008 bp->b_refcnt = 1; 2009 bp->b_dev = NODEV; 2010 bp->b_vnbufs.le_next = NOLIST; 2011 BIO_SETPRIO(bp, BPRIO_DEFAULT); 2012 } 2013 2014 void 2015 buf_destroy(buf_t *bp) 2016 { 2017 2018 cv_destroy(&bp->b_done); 2019 cv_destroy(&bp->b_busy); 2020 } 2021 2022 int 2023 bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock) 2024 { 2025 int error; 2026 2027 KASSERT(mutex_owned(&bufcache_lock)); 2028 2029 if ((bp->b_cflags & BC_BUSY) != 0) { 2030 if (curlwp == uvm.pagedaemon_lwp) 2031 return EDEADLK; 2032 bp->b_cflags |= BC_WANTED; 2033 bref(bp); 2034 if (interlock != NULL) 2035 mutex_exit(interlock); 2036 if (intr) { 2037 error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock, 2038 timo); 2039 } else { 2040 error = cv_timedwait(&bp->b_busy, &bufcache_lock, 2041 timo); 2042 } 2043 brele(bp); 2044 if (interlock != NULL) 2045 mutex_enter(interlock); 2046 if (error != 0) 2047 return error; 2048 return EPASSTHROUGH; 2049 } 2050 bp->b_cflags |= BC_BUSY; 2051 2052 return 0; 2053 } 2054